CBSE 12th

Hi Daksh,
Please visit the UBC website for admission requirement. It is clearly stated that the minimum average needed to fall within the competitive range is approximately 74% on a 33% pass scale, or 76% on a 40% pass scale. If you haven't checked the website yet, here is the link:
http://you.ubc.ca/applying-ubc/international-highschools-requirements/#india

Hi Kalvin,
In order to facilitate Shiksha experts to give you accurate and precise answers, it is important that you give us a little more information regarding the subject you are currently studying or pursued (stream: Arts, Science or Commerce) as well as your interests. Once you share this with us, our experts will be able to help you out better.

Hi Yash,
You may opt for the five year integrated programme after 12th. The selection process is rigorous and very competitive. In addition, you must clear an entrance exam followed by a personal interview. Please refer to the IIM Indore page for details:
http://www.iimidr.ac.in/academic-programmes/five-year-integrated-programme-in-management-ipm/
I hope it helped.

Hi Mamta,
Please visit the official website of CBSE to fill the improvement form and information on last dates. Last date is usually 15th of September.

Yes, you are eligible to get into DU with this score. However, the general category cut off for JEE this year was 100, thus you have to score more marks in JEE next year if you desire to get into good engineering colleges.

Hi, it's clear that you should go for engineering as you are much interested in Maths but you are also having another option that is B.Sc in Maths. It has also a good scope after doing B.Sc in Maths. You may go become a Professor of college or any university.
Good luck.

Hi Vishnu,
You can pursue class 12th from NIOS any time at any age.

If you want to pursue petroleum engineering without JEE, then you can give state exams conducted by various institutes offering this course. For e.g. UPES university has separate exam for admission into the engineering courses. You can give this exam and get admission into petroleum engineering.

The only options are taking maths as an additional subject but if you are in 12th, it would be difficult to register with board. Alternatively, take maths from NIOS and, you may join course of your choice. VIT does offer B.Tech in biotech for bio students where they can take up a bridge course in mathematics.

B.com and BBA are good options but you should choose the major according to your interest.
If you are interested to continue your study abroad, there are many programs available for you but for this, you have to prove your level of English by taking an IELTS or a TOEFL exam.